The present invention relates to an improved industrial robot device in which a work tool such as a cutting or a grinding tool is mounted at an end portion of an arm of the robot.
Conventionally, in cutting or grinding work, a work tool is mounted at a forward end of an arm of a robot and operations for achieving a desired purpose are performed while urging the work tool against a workpiece with a predetermined pressure or at a predetermined speed. Upon variations in load, however, the position and orientation of the work tool may suddenly change so that the work tool too closely approaches or separates from the workpiece. This phenomenon is especially prominent when the hardness of the workpiece is low.
If the work tool is mounted on a finger portion of a robot, which finger portion is connected with an arm portion by means of a helical spring (as disclosed, for example, in Japanese Utility Model Publication No. 39197/82), deformation or damage may be prevented in the work tool to some degree. However, since an arm portion and a finger portion are connected to each other through a helical spring in the robot, there is a disadvantage that abrupt changes in the position of the work tool cannot be prevented. That is, as the load changes, for example, if the work tool moves suddenly in a direction away from the workpiece, the helical spring will bend, making the work tool suddenly approach the workpiece due to a reaction force in a subsequent state and collide against the workpiece, thereby damaging both the work tool and the workpiece.